The present Applicant's published European patent application No. EP 1 048 608 describes apparatus for continuous sterilization of packaged foodstuffs which comprises a treatment, at high hydrostatic pressure, of beverages previously introduced into containers made of deformable material (for example, polyethylene terephthalate) which are sealed before treatment. The containers are introduced into suitable pressurization chambers which are then filled with a substantially incompressible liquid such as water and in which the hydrostatic pressure is imparted by a piston provided with a pressure-multiplier. The piston is driven by a mechanical device comprising a cam and operated by a motor.
However, in order to be able to perform an effective sterilization cycle, which in turn comprises pressurization and partial depressurization stages in succession, within the short time required by a continuous operation such as that described in the above-mentioned European patent application, the system for transmitting the pressure from the actuator to the piston must be extremely efficient, in other words, the time elapsing between the energization of the actuator and the reaching of the desired pressure inside the pressurization chamber must be as short as possible. A mechanical system such as that described above does not fully comply with these requirements.